Spring caging mechanism for a coil spring rail brake

Abstract

A rail brake includes a rigid enclosure which mounts under a crane so as to dispose the base end of the enclosure over and adjacent a rail. A spring carriage is mounted for vertical translation within the enclosure. Springs are mounted between the spring carriage and the top of the enclosure so that the springs are compressed when the spring carriage is elevated. A brake shoe is mounted under the carriage. Actuators are mounted between the spring carriage and the base end of the enclosure. Extension of the actuators compress the springs and elevate the brake shoe from the rail. Retraction allows the springs to drive the brake shoe against the rail. Elevation of the brake shoe aligns a pair of spline joints between the sides of the brake shoe and corresponding channel walls underneath the enclosure. Removable elongate keys provide the locking splines in the pair of spline joints.

What is claimed is: 
     
       1. A spring caging mechanism for a rail brake, wherein the rail brake includes a rail brake enclosure housing at least one spring acting downwardly against a brake shoe mounted underneath the rail brake enclosure so as to urge the brake shoe against a rail when the rail brake is positioned over the rail, the spring caging mechanism comprising:
 a caging frame depending downwardly from the rail brake enclosure so as to bracket the brake shoe which is mounted under the enclosure and linked to the at least one spring in the enclosure, wherein said caging frame includes a pair of substantially parallel walls defining a brake shoe channel therebetween, wherein said channel is sized so that the brake shoe is suspended and snug in said channel for vertical translation of the brake shoe in said channel between raised and lowered positions corresponding to a spring caging position and a rail engaging position respectively, 
 wherein opposed facing inner walls of said parallel walls include a corresponding pair of opposed facing first grooves, 
 and wherein an oppositely disposed pair of second grooves are formed in oppositely disposed outer surfaces of the brake shoe and positioned so that, when the brake shoe is in said raised position said first and second grooves are adjacent and aligned so as to form, collectively, a pair of key-receiving bores on opposite sides of the brake shoe when in its raised position, 
 a pair of elongate keys sized for snug sliding fitment into and along said pair of key-receiving bores, wherein when said keys are journalled in said bores the brake shoe is releasably locked in its raised position thereby caging the at least one spring in the rail brake enclosure. 
 
     
     
       2. The mechanism of  claim 1  wherein said pair of key-receiving bores and said first and second grooves are substantially horizontal. 
     
     
       3. The mechanism of  claim 2  wherein said pair of first grooves and said pair of second grooves are each aligned in a corresponding substantially horizontal plane. 
     
     
       4. The mechanism of  claim 3  wherein said first and second grooves are formed as corresponding channels so that said bores have a substantially square cross-section. 
     
     
       5. The mechanism of  claim 1  wherein said brake shoe channel is aligned so as to be substantially perpendicular to the rail when said rail brake is positioned over the rail. 
     
     
       6. The mechanism of  claim 5  wherein said caging frame further comprises oppositely disposed reinforcing members abutting and extending away from said parallel walls. 
     
     
       7. The mechanism of  claim 6  wherein said reinforcing members include at least one pair of oppositely disposed flanges mounted to so as to extend between said walls and the rail brake enclosure. 
     
     
       8. The mechanism of  claim 1  wherein said pair of elongate keys are a pair of separate linear keys.